It looks passive to me, due to the structure to be + past participle. However, if I take Z as a doer of the verb locate and change it around as in Z locates X, I am very confused with the meaning which I feel different from that in the "passive" format. I need to explain this to my students.

3 Answers
3

The source of the river was located by the three travellers 50 miles
inland.

However, in the construction X is located in Y, the -ed form of the verb is a participial adjective acting as the complement of the verb be. The question of voice does not arise. No one, I imagine, would think of sentences such as I am tired, This problem is complicated or They were very pleased as being any kind of passive. So it is with sentences like Paris is located in France and The key was located in the second drawer on the left.

EDIT:

Huddleston and Pullum, authors of ‘The Cambridge Grammar of the English Language’ distinguish between the ‘adjectival passive’ and the ‘be-passive’. In the sentence ‘Paris is located in France’, ‘located’ is the former, but the sentence ‘The source of the river was located by the three travellers’ is the latter. They point out that the difference is that when the verb preceding an adjectival passive is ‘be’, it can be substituted by another verb. So, we can say ‘Paris remains located in France’, but in the second sentence, there is no alternative to ‘was’.

@Barrie. There's an interesting difference between the examples you list in your last paragraph. With the first three it is possible to form a true passive construction: 'I am tired by your empty promises.' 'They were very pleased by the size of the meal.' 'This problem is complicated by the existence of different time scales.' (All plucked from Google.) But this doesn't work with 'located' in the sense of being somewhere (rather than finding it). I wonder if there are other past participles that behave like 'located / situated' and cannot be made passive.
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ShoeJan 15 '12 at 10:02

@Shoe: If I have understood your point correctly, I can offer ‘advanced’ (‘It was an advanced piece of engineering’) and ‘determined’ (‘They seemed very determined’).
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Barrie EnglandJan 15 '12 at 16:12

Can the passive voice ever use is + past participle? For example, putting "I typed the paper" into the passive, you can get, "the paper is being typed (by me)", "the paper was typed (by me)", "the paper was being typed (by me)", or "the paper has been typed (by me)". However, in "the paper is typed", the word "typed" is now an adjective, and you cannot say *"the paper is typed by me".
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Peter Shor Jan 29 '12 at 14:24

The Oxford Dictionary of English Grammar refers to this kind of construction as "pseudo-passive", i.e., it ".. neither has an active counterpart nor permits an agent." It contrasts pseudo-passives (which it also calls statal passives), where the verb to be is "arguably a copular verb," with true passives (actional passives), which can be converted to an active form with the agent as the subject.

Here's a good primer on the passive by Geoffrey Pullum, a contributor to Language Log and co-author of The Cambridge Grammar Of The English Language.

I’m not familiar with you source, but I think of the pseudo-passive as describing clauses like ‘I had my car washed’.
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Barrie EnglandJan 15 '12 at 17:17

@Barrie. Here is part of the text from the grammar dictionary entry on the pseudo-passive: "A construction, consisting of a part of the verb be + past participle, that resembles a passive, but which has neither an active counterpart, nor permits an agent."
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ShoeJan 29 '12 at 10:52